Mapping and testing circular economy product-level indicators: A critical review

Numerous indicators have been suggested as tools for assessing progress towards the circular economy (CE). However, it is unclear what specifically is captured by CE indicators and few studies have tested them on real cases. This review addresses this gap by describing and comparing the resource-related effects captured by existing resource-based product-level indicators and suggesting recommendations for their use and further development. First, the flows and processes quantified by product-level indicators are mapped on a novel flowchart model, which can also be used to select and develop indicators. Second, the indicators are tested on seven real cases. Third, indicator and life cycle assessment (LCA) results are compared. A significant divergence of indicators’ scope is found, where most capture a limited part of the product system. Moreover, important aspects of the CE are not captured: no indicator accounts for resource use in the use phase and there is limited attention to lifetime extension strategies. Additional limitations are the difficulties to assess multiple use-cycles and that most indicators cannot capture absolute mass variations, thus neglecting mass reduction strategies. The testing reveals that using a set of single-focus indicators may be necessary to outline trade-offs. Multi-focus indicators are sometimes harder to analyse but provide a more comprehensive assessment. The testing also illustrates that indicator and LCA results are not necessarily aligned. The latter provides information on environmental impacts and can point to trade-offs between impact categories such as climate change, resource use and land use, indicating that CE indicators cannot easily replace LCA